Apparatus and Method for Measuring Received Power and Determining Emission Pattern and Transmitting Power in Radio Frequency Identification Reader

摘要

A device and a method for determining an emission pattern and transmission power in an RFID reader by measuring received power are provided to control the emission pattern of an antenna for transmitting an RF signal and prevent emission of the excessive RF signal by measuring the power of the RF signal received from an RFID tag. A signal detector(350) generates control signals according to a measured value by measuring the power of the RF signal received from the RFID tag. An operation controller(390) transmits the RF signal to the RFID tag, and receives the RF signal from the RFID tag by using a full directional antenna(300) or a directional antenna(310) according to the control signals. A power amplifier(365) amplifies the RF signal transmitted to the RFID tag to a different power level according to the control signals. If the RFID tag is not recognized or the measured power of the received RF signal is smaller than a threshold, the operation controller performs control for using the directional antenna. If the measured power of the received RF signal is bigger than the threshold when the direction antenna is used, the operation controller makes gain of the power amplifier small.